Anode connection structure of organic light-emitting diode and manufacturing method thereof

ABSTRACT

A method is provided for manufacturing an anode connection structure of an organic light-emitting diode. The anode connection structure includes: a thin-film transistor and an anode of an organic light-emitting diode arrange don the thin-film transistor. The thin-film transistor includes a low-temperature poly-silicon layer formed on a substrate, a gate insulation layer formed on the low-temperature poly-silicon layer, a gate formed on the gate insulation layer, a protection layer formed on the gate, and a source/drain formed on the protection layer. The method includes a step of forming a hole in the thin-film transistor to expose the low-temperature poly-silicon layer and a step of forming an electrically conductive layer in the hole for direct engagement with the low-temperature poly-silicon layer to serve as an anode and also the source/drain of the thin-film transistor. The anode of the organic light-emitting diode is thus directly connected to the low-temperature poly-silicon layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional application of co-pending patent application Ser.No. 14/008,607, “Anode Connection Structure of Organic Light-EmittingDiode and Manufacturing Method Thereof”, filed on Sep. 30, 2013.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of light-emitting diodes, andin particular to an anode connection structure of an organiclight-emitting diode and a manufacturing method thereof.

2. The Related Arts

An organic light-emitting diode display (OLED), which is also referredto as an organic electroluminescent diode, is a novel displayingtechnology of which the development was dated back to the middle of the20th century. The organic electroluminescent diode has variousadvantages over a liquid crystal display, such as being fully solidstate, active emission of light, high brightness, high contrast, beingultra thin, low cost, low power consumption, fast response, wide viewangle, wide range of operation temperature, and being capable offlexible displaying. The structure of an organic electroluminescentdiode generally comprises a substrate, an anode, a cathode, and anorganic function layer and the principle of light emission thereof isthat multiple layers of organic materials that are of extremely smallthickness is formed between the anode and the cathode through vapordeposition, whereby positive and negative carriers, when injected intothe organic semiconductor films, re-combine with each other to generatelight. The organic function layer of the organic electroluminescentdiode is generally made up of three function layers, which arerespectively a hole transport layer (HTL), an emissive layer (EML), andan electron transport layer (ETL). Each of the function layers can be asingle layer or more than one layer. For example, the hole transportlayer may sometimes be further divided into a hole injection layer and ahole transport layer and the electron transport layer may also bedivided into an electron transport layer and an electron injectionlayer. However, they are of substantially the same function and are thuscollectively referred to as the hole transport layer and the electrontransport layer.

Currently, the manufacture of a full-color organic electroluminescentdiode is generally done with three methods, which are RGB juxtapositionand individual emission method, white light in combination with colorfilter method, and color conversion method, among which the RGBjuxtaposition and individual emission method is most promising and hasthe most practical applications. The manufacturing method thereof isthat red, green, and blue use different subject and objectlight-emitting materials.

The organic light-emitting diodes can be classified in two types,according to the method of driving, which are active driving and passivedriving, namely direct addressing and TFT (Thin-Film Transistor) matrixaddressing. The active driving type organic light-emitting diode is theso called active matrix organic light emitting device (AMOLED).

The AMOLED has a pixel circuit and a compensation circuit that are muchmore complicated than those of a liquid crystal display (LCD) and thus,for the conventional AMOLED products, the available number of pixels perinch (PPI) is less than 280, rendering the resolution relatively low.

Referring to FIGS. 1 and 2, schematic views are given to show aconventional anode connection structure of an organic light-emittingdiode. An anode 100 is electrically connected to a low-temperaturepoly-silicon layer 50 by driving the source/drain terminal 300 of thethin-film transistor. Due to the arrangement of a metal layer of thesource/drain terminal 300, the distance between switching thin-filmtransistors on the two sides is increased, whereby the area of the pixelis relatively large and thus the number of pixels per inch is reduced,leading to a relatively low resolution.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an anode connectionstructure of an organic light-emitting diode, which has a simplestructure, a low cost, a small pixel area, and a high resolution.

Another object of the present invention is to provide a manufacturingmethod of an anode connection structure of an organic light-emittingdiode, which has a simply manufacturing process and can effectivelyreduce a pixel area and improve resolution.

To achieve the objects, the present invention provides an anodeconnection structure of an organic light-emitting diode, whichcomprises: a thin-film transistor and an anode of an organiclight-emitting diode arranged on the thin-film transistor. The thin-filmtransistor comprises a low-temperature poly-silicon layer formed on asubstrate, a gate insulation layer formed on the low-temperaturepoly-silicon layer, a gate formed on the gate insulation layer, aprotection layer formed on the gate, and a source/drain formed on theprotection layer. The anode of the organic light-emitting diode isconnected to the low-temperature poly-silicon layer.

A planarization layer is arranged between the thin-film transistor andthe anode of the organic light-emitting diode.

The substrate comprises a glass substrate.

An isolation layer is formed between the substrate and thelow-temperature poly-silicon layer.

The anode of the organic light-emitting diode comprises one of an indiumtin oxide layer, an indium zinc oxide layer, an aluminum layer, a silverlayer, and a molybdenum layer or a lamination thereof.

The present invention also provides an anode connection structure of anorganic light-emitting diode, which comprises: a thin-film transistorand an anode of an organic light-emitting diode arranged on thethin-film transistor, the thin-film transistor comprising alow-temperature poly-silicon layer formed on a substrate, a gateinsulation layer formed on the low-temperature poly-silicon layer, agate formed on the gate insulation layer, a protection layer formed onthe gate, and a source/drain formed on the protection layer, the anodeof the organic light-emitting diode being connected to thelow-temperature poly-silicon layer;

wherein a planarization layer is arranged between the thin-filmtransistor and the anode of the organic light-emitting diode.

The substrate comprises a glass substrate.

An isolation layer is formed between the substrate and thelow-temperature poly-silicon layer.

The anode of the organic light-emitting diode comprises one of an indiumtin oxide layer, an indium zinc oxide layer, an aluminum layer, a silverlayer, and a molybdenum layer or a lamination thereof.

The present invention further provides a manufacture method of an anodeconnection structure of an organic light-emitting diode, which comprisesthe following steps:

(1) providing a substrate, wherein the substrate comprises a thin-filmtransistor formed thereon;

(2) forming a planarization layer on the thin-film transistor;

(3) forming a hole in the planarization layer and the thin-filmtransistor to expose the low-temperature poly-silicon layer of thethin-film transistor; and

(4) forming an electrically conductive layer on the planarization layerand the exposed low-temperature poly-silicon layer and patternizing theelectrically conductive layer to form a new source/drain on thelow-temperature poly-silicon layer and also forming an anode of anorganic light-emitting diode on the planarization layer, the anode ofthe organic light-emitting diode being connected to the newsource/drain.

The thin-film transistor comprises the low-temperature poly-siliconlayer that is formed on the substrate, a gate insulation layer formed onthe low-temperature poly-silicon layer, a gate formed on the gateinsulation layer, a protection layer formed on the gate, and asource/drain formed on the protection layer.

The substrate comprises a glass substrate.

An isolation layer is arranged between the substrate and thelow-temperature poly-silicon layer.

The electrically conductive layer comprises one of an indium tin oxidelayer, an indium zinc oxide layer, an aluminum layer, a silver layer,and a molybdenum layer or a lamination thereof.

The efficacy of the present invention is that the present inventionprovides an anode connection structure of an organic light-emittingdiode and a manufacturing method thereof, wherein the anode of theorganic light-emitting diode is directly connected to a low-temperaturepoly-silicon layer of a thin-film transistor without interconnectiontherebetween achieved with a source/drain metal layer so as toeffectively reduce the distance between two adjacent switching thin-filmtransistors, thereby effectively reducing the pixel area, increasing thenumber of pixels in a unit area (each inch), and improving theresolution of a panel using the anode connection structure of theorganic light-emitting diode.

For better understanding of the features and technical contents of thepresent invention, reference will be made to the following detaileddescription of the present invention and the attached drawings. However,the drawings are provided for the purposes of reference and illustrationand are not intended to impose undue limitations to the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The technical solution, as well as beneficial advantages, of the presentinvention will be apparent from the following detailed description of anembodiment of the present invention, with reference to the attacheddrawings. In the drawings:

FIG. 1 is a schematic view showing the structure of a conventional anodeconnection structure of an organic light-emitting diode;

FIG. 2 is a top plan view of the conventional anode connection structureof the organic light-emitting diode;

FIG. 3 is a schematic view showing the structure of an anode connectionstructure of an organic light-emitting diode according to the presentinvention;

FIG. 4 is a top plan view of the anode connection structure of theorganic light-emitting diode according to the present invention; and

FIG. 5 is a flow chart illustrating a manufacturing method of an anodeconnection structure of an organic light-emitting diode according to thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

To further expound the technical solution adopted in the presentinvention and the advantages thereof, a detailed description is given toa preferred embodiment of the present invention and the attacheddrawings.

Referring to FIGS. 3 and 4, the present invention provides an anodeconnection structure of an organic light-emitting diode, whichcomprises: a thin-film transistor 20 and an anode 40 of an organiclight-emitting diode arranged on the thin-film transistor 20. Thethin-film transistor 20 comprises a low-temperature poly-silicon layer24 formed on a substrate 22, a gate insulation (GI) layer 26 formed onthe low-temperature poly-silicon layer 24, a gate (not shown) formed onthe gate insulation layer 26, a protection layer (ILD) 27 formed on thegate, and a source/drain (SD) 28 formed on the protection layer 27. Theanode 40 of the organic light-emitting diode is directly connected tothe low-temperature poly-silicon layer 24 in order to reduce thedistance between two adjacent switching thin-film transistors and thuseffectively reducing the pixel area, increasing the number of pixels ina unit area (each inch), and improving the resolution of a panel usingthe anode connection structure of the organic light-emitting diode.

The thin-film transistor 20 comprises a switching thin-film transistorand a driving thin-film transistor. The anode 40 of the organiclight-emitting diode is connected to the low-temperature poly-siliconlayer 24 of the driving thin-film transistor.

Further arranged between the thin-film transistor 20 and the anode 40 ofthe organic light-emitting diode is a planarization layer 60, whichavoids influence of displaying performance caused by corrosion andbreaking resulting from impurities contained in the anode 40 of theorganic light-emitting diode.

Specifically, the substrate 22 is a glass substrate and the anode 40 ofthe organic light-emitting diode comprises one of an indium tin oxide(ITO) layer, an indium zinc oxide (IZO) layer, an aluminum (Al) layer, asilver (Ag) layer, and a molybdenum (Mo) layer or a lamination thereof.

It is noted that an isolation layer 29 is further arranged between thesubstrate 22 and the low-temperature poly-silicon layer 24 to preventimpurities from spreading to the thin-film transistor 20 to causemalfunctioning of the thin-film transistor 20.

Referring to FIG. 5, with collaborative reference to FIGS. 3 and 4, thepresent invention further provides a manufacturing method of an anodeconnection structure of an organic light-emitting diode, which comprisesthe following steps:

Step 1: providing a substrate 22, wherein the substrate 22 comprises athin-film transistor 20 formed thereon.

The substrate 22 is a glass substrate. The thin-film transistor 20comprises a low-temperature poly-silicon layer 24 formed on thesubstrate 22, a gate insulation layer 26 formed on the low-temperaturepoly-silicon layer 24, a gate formed on the gate insulation layer 26, aprotection layer 27 formed on the gate, and a source/drain 28 formed onthe protection layer 27.

The thin-film transistor 20 comprises a switching thin-film transistorand a driving thin-film transistor.

Step 2: forming a planarization layer 60 on the thin-film transistor 20.

The planarization layer 60 functions to avoid influence of displayingperformance caused by corrosion and breaking resulting from impuritiescontained in the anode 40 of the organic light-emitting diode.

Step 3: forming a hole in the planarization layer 60 and the thin-filmtransistor 20 to expose the low-temperature poly-silicon layer 24 of thethin-film transistor 20.

Specifically, a masking process is applied to form a hole in theplanarization layer 60 and the driving thin-film transistor at alocation corresponding to the source/drain 28 in order to expose themetal layer that serves as the source/drain 28; and then, the metallayer of the source/drain 28 is etched off to expose the low-temperaturepoly-silicon layer 24 located thereunder.

Step 4: forming an electrically conductive layer on the planarizationlayer 60 and the exposed low-temperature poly-silicon layer 24 andpatternizing the electrically conductive layer to form a newsource/drain 280 on the low-temperature poly-silicon layer 24 therebycompleting the entirety of the driving thin-film transistor, and at thesame time, forming an anode 40 of the organic light-emitting diode onthe planarization layer 60. Since the new source/drain 280 and the anode40 of the organic light-emitting diode are both formed of theelectrically conductive layer, in the manufacture process, the anode 40of the organic light-emitting diode and the new source/drain 280 are notcut to separate from each other and the anode 40 of the organiclight-emitting diode is directly connected to the low-temperaturepoly-silicon layer 24, so that the distance between two adjacentswitching thin-film transistors can be effectively reduced, therebyeffectively reducing the pixel area, increasing the number of pixels ina unit area (each inch), and improving the resolution of a panel usingthe anode connection structure of the organic light-emitting diode.

In the instant embodiment, the electrically conductive layer comprisesone of an indium tin oxide layer, an indium zinc oxide layer, analuminum layer, a silver layer, and a molybdenum layer or a laminationthereof.

It is noted that an isolation layer 29 can be further arranged betweenthe substrate 22 and the low-temperature poly-silicon layer 24 toprevent impurities from spreading to the thin-film transistor 20 tocause malfunctioning of the thin-film transistor 20.

In summary, the present invention provides an anode connection structureof an organic light-emitting diode and a manufacturing method thereof,wherein the anode of the organic light-emitting diode is directlyconnected to a low-temperature poly-silicon layer of a thin-filmtransistor without interconnection therebetween achieved with asource/drain metal layer so as to effectively reduce the distancebetween two adjacent switching thin-film transistors, therebyeffectively reducing the pixel area, increasing the number of pixels ina unit area (each inch), and improving the resolution of a panel usingthe anode connection structure of the organic light-emitting diode.

Based on the description given above, those having ordinary skills ofthe art may easily contemplate various changes and modifications of thetechnical solution and technical ideas of the present invention and allthese changes and modifications are considered within the protectionscope of right for the present invention.

What is claimed is:
 1. A method for manufacturing an anode connectionstructure of an organic light-emitting diode, comprising the followingsteps: providing a substrate, wherein the substrate comprises athin-film transistor formed thereon; forming a planarization layer onthe thin-film transistor; forming a hole in the planarization layer andthe thin-film transistor to expose the low-temperature poly-siliconlayer of the thin-film transistor; and forming an electricallyconductive layer on the planarization layer and the exposedlow-temperature poly-silicon layer to be in direct contact engagementwith the low-temperature poly-silicon layer and patternizing theelectrically conductive layer to form a new source/drain on thelow-temperature poly-silicon layer and also forming an anode of anorganic light-emitting diode on the planarization layer, the anode ofthe organic light-emitting diode being connected to the new source/drainand in direct contact engagement with the low temperature poly-siliconlayer.
 2. The method as claimed in claim 1, wherein the thin-filmtransistor comprises the low-temperature poly-silicon layer that isformed on the substrate, a gate insulation layer formed on thelow-temperature poly-silicon layer, a gate formed on the gate insulationlayer, a protection layer formed on the gate, and a source/drain formedon the protection layer.
 3. The method as claimed in claim 2, whereinthe substrate comprises a glass substrate.
 4. The method as claimed inclaim 2, wherein an isolation layer is arranged between the substrateand the low-temperature poly-silicon layer.
 5. The manufacturing methodof an anode connection structure of an organic light-emitting diode asclaimed in claim 2, wherein the electrically conductive layer comprisesone of an indium tin oxide layer, an indium zinc oxide layer, analuminum layer, a silver layer, and a molybdenum layer or a laminationthereof.